Neptune: Still Springtime After All These Years
Credit:
L. Sromovsky and P. Fry (Univ.
Wisconsin - Madison) et al.,
NASA
In the 1960s spring came to the southern hemisphere of
Neptune,
the Solar System's outermost gas giant planet.
Of course, since Neptune orbits the Sun once every 165
earth-years,
it's still springtime for southern Neptune, where
each
season lasts over four decades.
Astronomers
have found that in recent years
Neptune has been getting brighter
as illustrated in this Hubble Space Telescope image made in 2002.
Compared
to Hubble
pictures taken as early as 1996,
the 2002 image shows a dramatic increase in reflective
white cloud bands in Neptune's southern hemisphere.
Neptune's
equator is tilted 29 degrees from the plane of its orbit,
about the same as Earth's 23.5 degree tilt, and
Neptune's weather
seems to be dramatically responding to the
similar relative seasonal increase in sunlight -- even though
sunlight is 900 times
less intense for the distant gas giant than for planet Earth.
Meanwhile, summer is really just around the
corner, coming to
Neptune's southern hemisphere in 2005.